The scene at first resembles many that play out daily in the war-torn Red Zone of southern Afghanistan: a pair of Black Hawk helicopters descend on a hillside near the country’s southern border with Pakistan. As the choppers land, U.S. marines leap out, assault rifles ready. But then geologists sporting helmets and heavy ceramic vests jump out, too. The researchers are virtually indistinguishable from the soldiers except that they carry rock hammers instead of guns. A human chain of soldiers encircles the scientists as they step forward on the dusty ground.

“The minute you get off, you go into geologist mode,” says Jack H. Medlin, director of the U.S. Geological Survey’s activities in Afghanistan. “You forget, basically, that these guys are around—unless you try to get out of the circle.”